Annealing furnace construction



Oct. 20, 1942. w, J, KRA|L|NG 2,299,546

ANNEALING FURNACE CONSTRUCTION Y Filed oct. e, 1941 2 snets-sheet 1 ATTORNEY Oct. 20, 1942. Vw KRAlLlNG l 2,299,546

ANNEALING FURNACE CONSTRUCTION Filed oct. e, 1941 v z'she'ets-sheet 2 INVENTOR ATTORNEYS Patented Oct. 20, 1942 UNITED STATES PATENT OFFICE.

2,299,546 s ANNEALING FUnNAcE CONSTRUCTION William J. Krailing, Bridgeport, Conn., assignor to Bridgeport Brass Company, Bridgeport, Conn., a corporation of Connecticut Application october s, `i941, serial No. 413,732

(ci. zes-) 7 claims.

The present invention relates to loading mechanism to charge and discharge a continuous heat treating furnace withmaterial requiring heat treatment.

In continuous annealing furnaces, for example, of the driven-roller type involving continuous motion of the annealing charge through the furnace, present practice, so far as is known, requires repeated opening and closing of a door or doors each time a charge is delivered to or discharged from the furnace. This necessarily involves large heat losses, high fuel costs, and permits the introduction of unwanted air and oxygen to the furnace with each charging or discharging operation with consequent undesired oxidation of metal on surfaces being annealed in the furnace.

An, object of this invention is to eliminate the foregoing objectionable defects by provision of a novel structure which will permit charges such as coils of brass or other metal products to be delivered to and discharged from the furnace without the necessity of opening or closing doors.

This is accomplished in the present invention by utilizing constructions at the furnace adits and exits based upon the principles of a revolving door, i. e. a vestibule at each adit or exit equipped with revolving door flaps which serve effectively to seal the interior of the furnace from atmosphere while permitting charges to be delivered to andfrom' the furnace. I

Advantages of such constructions are: elimination of heat losses, lowered fuel costs, elimination of oxidation difficulties in the furnace, and more convenient and less laborious charging. and discharging of the furnace with consequent better control of the annealing process.

To the accomplishment of the foregoing and such other objects as may hereinafter appear, this invention consists in the construction and arrangement of parts to be hereinafter described, and then sought to be defined in the appended claims, reference being had to the accompanying drawings forming a part hereof and which show, merely for the purposes of illustrative disclosure,

-preferred embodiments of the invention, it being expressly understood, however, that various changes may be made in practice within the scope of the claims without digressing from the inventive idea.

In the drawings in which similar reference characters denote corresponding parts:

Fig. 1 is a side elevation of a furnace equipped with the novel loading and discharging mechanism;

Fig. 2 isa transverse section taken along line 2-2 of Fig. 1 and viewed in the direction of the arrows;

Fig. 3 'is an enlarged vertical section taken along line 3-3 of Fig. 2 viewed in the direction of the arrows; and

Fig. 4 is a fragmentary vertical sectional view on an enlarged scale of details of structure taken s along line 4-4 of Fig. 2 and viewed in the direc- -tion of the arrows; and

extends outwardly of the wall I I through a suitable packing gland I5 and each shaft I4 has a drive member such as a. sprocket I6 fixed thereto. The sprockets I6 of the sets of rollers R and R' are arranged'in longitudinal alignment respectively at the front and rear of the furnace. An

endless chain I1 meshing with each of the sprockets I6 of the front set of rollers R and suitably tensioned bythe idler sprockets I8 also meshes with a driven sprocket I9. The latter is driven by any suitable means. In the embodiment shown it is mounted on the driven shaft 20 of a. reduction geared motor 2 I. In this manner each roller I3 of the front set of rollers R can be rotated. A similar endless chain I'Ia driven from the same motor 2I or a'. separate motor serves to rotate the rear set of rollers R'. While endless chain drives for rotating the rollers I3 are shown, it should be understood that pulleys and endless bands or gears or any other common drive system may be utilized for rotating the rollers I3 of the sets R and R'. The two sets of rollers R and R' constitute driven roller conveyors for advancing coils C or other articles being heat treated through the furnace.

Means are provided both for conveying articles to the furnace I0 and for delivering heat treated articles leaving the furnace to other devices. Both admission to and delivery from the furnace must be of such a nature as to prevent effectively the escape of heat and gases from the furnace or the admission of air or deleterious gases thereto.

To this end, the adit end A and exit end B of the furnace are provided with vertically arranged cylindrical vestibules 15a, 25h, 25e,- 25d, two being shown arrangedat each end. These vestibules may be continuations of the furnace 'spaced arcuate recesses A rotatable door 28a consisting of four door flaps or partitions 29 arrangedat right angles to each other on a central rotatable axle 30 is arranged in the vestibule a (Fig. 3) The axle is arranged to lie in the longitudinal axis of said vestibule 25a. The lower end 3| of the axle 30 is rotatably borne in a bearing 32 suitably positioned at the bottom of the vestibule. The upper end 33 of the axle extends through' the top wall 34 of the vestibule 25a and through a suitable bearing 35 positioned on the said top wall. vEach flap 29 is provided on an outer edge 29'? thereof with a sealing strip 36 of asbestos or the like. Each flap is so admeasured in width that its'sealing strip 36 engages in sealing relationship with the cylindrical wall of vestibules 26a. Each `flap 29 is also so admeasured in height that its top edge 29" abuts the inner face of said top wall 34. The flaps may be at other than right angles.

An intermittent drive element 31 is fixed to the shaft end 33. A driving member 38 supported on and locked to a stub shaft 39 is coupled with the 'element 31 as will be presently described.

ShaftV 39 is adapted to be driven by a gear 40 n thereon,which in turn meshes with a gear 4| carried on a drive shaft 42 which may be driven from a power source (not shown) in any desirable way as by a chain 43 coupling the source to a sprocket 44 on the shaft 42.

' The intermittent drive element 31 comprises a gear portion 31a. A second disk-like portion 31b overlies the gear portion 31a. This disk-like portion has a diameter substantially equal to the overall diameter of the gear portion 31a. Equi- 31c are arranged in the peripheral edge of disk portion 31h and overlie theteeth of gear portionl 31a.

The ydriving member 38 comprises a segmental gear portion 38a whose teeth may mesh with the gear portion 31a. This gear segment 38h and the gear 31a are so admeasured as to rotate the shaft 39 a quarter turn for each complete rotation vof the member 38. A disk-like portion 38h overlies the segmental gear 38a. This portion has an arcuate recess 38e overlying the teeth of the segmental gear 38a. This,disklike portion 38h and disk-like portion 31b are so admeasured that the peripheral surface of disk 38h normally engages in one of the arcuate recesses 31e of disk 31h while gear segment 38a is out of mesh' with gear 31a thus locking disk 31h against accidental` rotation during idling periods of the intermittent rotation. When gear segment 38a meshes with gear 31a,'the recess 38e faces disk 31e and the latter is unlocked and is free to rotate..

The intermittent drive system comprising the parts just described constitutes thus a means for periodically rotating the shaft carried door flaps 29 a quarter of a turn and for locking them in each successive position during the idling period, i. e, while gear segment 38a is out of mesh with gear 31a. Other forms of intermittent drive are equally applicable and the described form is simply by way of example.

vIdentical rotatable doors 28h, 28o and 28d are provided respectively for the vestibules 25h, 25o and 25d. Each is intermittently driven in the same way as rotatable door 28a. All are adapted to be driven from the same power source used to drive door 28a through suitable shafting, gearing and the like as is well understood. If desired each door may, of f course, be independently driven.

Inclined gravity-feed roller conveyors 45, 46

respectively feedcoils C through the openings 21a, 21h of the cylindrical adit vestibules 25a, 25b into the first quadrants I of the latter. Roller conveyors 41, 48 arranged within the respective vestibules 25a, 25h in their respective second quadrants II lead into the interior of the furnace terminating at such" a level in the third quadrants III that the power driven roller conveyors R, R' extending into the third quadrants through the respective openings 26a, 2Gb constitute respective continuations of the respectiva conveyors, 41, 48.

Coils C to be treated pass one ata time from the conveyors 45, 46 into the respective openings 21a, 21h in the rst quadrant I of the respective vestibules 25a, 25o. As the door aps 29 rotate in the directions of the respective arrows, the coils C delivered in the first quadrants I of vestibules 25a, 25h are moved into the second quadrants II of these vestibules by a quarter turn rotation of the respective doors and onto th'e respective roller conveyors 41, 48. The next succeeding quarter turn rotation of the respective door flaps 29 causes the latter to deliver` the coils C in their respective second quadrants II'to the third quadrants III of the respective vestibules 25a, 25h. In these 'third quadrants III the coils C are moved by the partitions orV flaps 29 from the respective roller conveyors 41, 48 onto the respective power driven roller conveyor R, R and are then conveyed by the latter through the furnace I0 at the speed determined by the drive speedof rollers |3. The coils C are delivered in spaced relationship to the power roller conveyors |3 in the furnace depending upon the frequency of the intermittent rotation of the respective doors 28a, 28h.

At the exit end B of the furnace, the coils C are delivered in the third quadrants IIIof vestibules 25e, 25d through the respective openings 26C, 26d to the respective roller conveyors 50, 5| arranged therein. The flaps 29 of intermittently rotated doors 28o, 28d of these vestibules first move the respective coils into the respective second quadrants II of the said vestibules 25c, 25d.

On the next quarter turn of the respective doors 28e, 28d, the coils are delivered thereby to the respective third quadrants III of said vestibules and onto the respective gravity roller feed con-I veyors 52, 53.

These conveyors 52, 53 lead the emerging coils C through a. cooling chamber and a quenching chamber 6| of any well-known type, or may lead the coils to other apparatus to be treated. The relative timing of the intermittent rotation of the doors 28a, 28h, 28e, 28d and the conveying speed of rollers I3 is such that delivery to and discharge of coils from the furnace is automatically maintained at a uniform rate.

It is desirable at the adit end A of the furnace to remove air or deleterious gases surrounding the coils C prior to their entry' into the furnace in the third quadrants III of the respective vestibules 25a, 2517.

Identical construction for this purpose is provided in vestibules 25a and 25h only. Since the construction is identical, only that in vestibule* 25a is described. Herein vent holes 65 are pro-.- vided in each quadrant of the top 34 of said vestibuie 25a. Each door iiap 29 of door 28a has Vent holes 66 therein. 'These holes 66are normally closed over by suitable shutter slides 61 slidably mounted on the respective door flaps 29. Thesel slides are adapted to be moved by suitable means as levers 68. The respective levers 68 are suitably pivoted at 99 to the respective flaps 29 and plvotally Joined at to the respective slides I1. The levers are each provided with a cam follower 1I which is adapted to move over a cam 12 suitably supported from the top 34. The door flaps are provided with clearance slots 13 for the cam. These slots may have suitable sealing shutters 1I rattached to the levers 88 to prevent gas leakage through the slots 1l.

The cam 12 is so arranged that it will actuate the slides B1 one at a time and only that one of the slides of the particular flapy 2l which sepa rates quadrant compartments II and III to clear `the openings or holes 68 of that particular flap 29 so that gases from the furnace may enter lquadrant compartment. II from quadrant compartment III through these holes and scavenge the air from quadrant compartment II driving it out through the ventP holes 95 over quadrant II. When the door 25a is rotated through the next quarter turn, the aforementioned particular flap 29 of course moves to a new position. The cam roller 1I thereof moves ci! the high part of cam 12 and permits the particular slide 61 to close its associated vent holes 66. At the same time the slide 61 of the next succeeding door ap which comes into the position Just vacated by the first flap 29, opens its associated vent holes 89. In this way' scavenging of air from the coil in quadrant compartment II always occurs before it 1s delivered to quadrant compartment III.`

The scavenging control elements just described are provided in i'dentical manner for the door 25h and its flaps 29. No such devices are necessary with respect to the doors 25c and 25d at the exit end of the furnace.

Any suitable means are `provided to prevent leakage of air into the furnace or escape of gases therefrom around the lower edges 29"' of the door flaps 29 and the rollers of the various conveyors. To this end the base or bed i2 of the furnace is built up at l12a (Figs. 3 and 4) below the various rollers in compartments or quadrants I, II and III of each of the vestibules 25a, 25h, 25p and 25d, there being just suillcient clearance to permit free rotation of the conveyor rollers. In addition a radially extending upstanding rib I2c is provided in the bedr 12a under each of the three door flaps 29 defining respectively the quadrant compartments I, II and HI of each vestibule shown in Fig. l. Suitably attached on the upper surface of each rib is a sealing strip 15 of asbestos or other suitable material. 'These strips 15 and supporting ribs are so admeasured in height that during the stationary periods of s edge 29' of the door flaps. The rollers too may move as described to open vent holes 68 permitting scavenging of air in quadrant compartments II by the furnace gases. The doors are then given another quarter turn delivering the coils from quadrant compartments II to quadrant compartments III and onto the driven conveyor rollers I3 which move the coils through the iur-l nace ill toits exit end B where they are delivered to quadrant compartments III of the vestibules` 2ic, 25:1. From these quadrant compartments the coils are delivered step by step with each quarter turn of the doors 28e, 28d and delivered in the first quadrants I of the vestibules 25e, 25d

to the respective gravity roller conveyors 52, 53,

whence, as described, the coils are moved to other apparatus such as cooling chamber 60 and quenching chamber 6|.

In Fig. 5 a modified form of construction is shown. The furnace l0' of similar type as that of furnace I0 may be supplied either with coils C or bars T. Only the adit end of the furnace III' is shown, the construction at the exit end being substantially identical. In this construction the driven rollers i3 of roller conveyors Y, Y' within the furnace are driven respectively by., chains l1' in identical manner as the rollers I3 of Figs. 1-3.

A pair of straight-through, gravity-feed roller conveyors 80, 8| are substituted for the conveyors 45 and 49 of Fig. 1. These conveyors 80 and 9| terminate within -the furnace at the respective adit or front terminals of the power driven roller conveyors Y, Y.

A similar set of straight-through, gravity-feed roller conveyors (not shown) are provided at the exit terminals of the said power drivenA roller conveyors I3.

Entrance to the furnace I0 at its front end A is through the pair of cylindrical vestibules 95a, 85h. The walls of these vestibules have openings respectively in their first quadrants I and their fourth quadrants IV.

In vestibule 8517 is a rotatable door 86h consisting of four flaps 81 arranged normally at right angles to each other on a rotatable shaft 88. The respective flaps 81 are pivotally supported at 89 from the shaft 88 and are normally maintained at right angles to each other by the removable cross braces 90 whose ends are removably attached in any suitable way at 9| to the respective flaps 81. Removal of any set of cross braces 90 from any one of the flaps 91 permits thatflap to be -turned on its hinge 89. For example, removal of4 the cross braces 90' shown in dotted line in Fig. 4 permits the flap 89' Ialsofshown in dotted line tobe folded back to the full line position 89".v

Identical door structure (not shown) is provided in the vestibule a and in two vestibules (not shown) similarly arrangedl at the exit end of the furnace. 'I'he door naps 89 have sealing strips 96a for the same purpose as strips 33 of Figs. 1-3. .v

These doors 86a, etc. are intermittently driven through intermittent gear elements 31', 38' and associated parts in identical manner as the intermittent doors 29a, etc. described with respect to Figs. 1-4.

While being intermittently rotated. .coils from the roller conveyors 80, 8| are periodically transferred from compartments I to compartments IV of the vestibules by the rotation of the doors 86a, 86h in the direction of the arrows. Except during the actual rotary movement of the doors 96a, 86h the passageway from the outside to the inside of the furnace through the respective vestibules is blocked off by a door flap 81 so that heat loss from the furnace is minimized. When it is desired to feed long bars to the furnace the driving of the intermittent gears 31', 38 for the respective rotary doors 86 is stopped in any well known manner for example, by disconnecting the chain 43. The door cross braces 90' are removed and the door flaps 89 pivoted back to 89" as shown leaving a clear path for movement .of the bars T fromthe rollerI conveyors 80, 8| onto the driven feed rollers I3' in the furnace IU.-

Identical vestibule and rotating door structure (not shown) at the exit end of the furnace is similarly arranged to permit delivery of the bars T from the driven feed rollers I3' vto suitable conveyor rollers (not shown) at the exit end of furnace I.

`When the structure is arranged for treating of bars T, instead of treating such bars, the furnace may be shut down. Now being open at both ends` to atmosphere, it cools rapidlyto 'permit repairs in its interior.

Modifications in structure are contemplated within the scope of the appended claims. There is no intention of limitation to the details shown and described.

What is claimed is:

1. In a heat-treating furnace or the like, means for charging and discharging material therefrom without substantial heat losses or the introduction of deleterious gases comprising vestibule structure at each adit and exit of the furnace, rotatable door structure in each vestibule, means for rotating said door structures intermittently to periodically charge and discharge `material from said furnace, and sealing means in conjunction with each of said door structures, said rotating means comprising intermittently-drivable gears associated with said door structures, segmental driving gears each adapted to mesh with one of said drivable gears, and interengaging means associated with said gears for locking the door structures against accidental rotation when said gears are out of mesh.

2. In a heat-treating furnace or the like, means for charging and discharging material therefrom Without substantial heat losses or the introduction of deleterious gases comprising vestibule structure at each ladit andexit of the.furnace, rotatable door structure in each vestibule, and means for rotating each of said door structures a part revolution intermittently to periodically charge and discharge material from said furnace, said rotating means comprising intermittently Ydrivable gears associated with said door structures, segmental driving gears each adapted to mesh with one of said drivable gears, and interengaging means associated with said gears for locking-the door structures against accidental rotation when said gears are out of mesh.

3.-;Ln a heat-treating furnace or the like, means-for charging and discharging material therefrom Without substantial heat losses or the introduction of deleterious gases comprising vestibule structure 'at each adit and exit of the furnace, rotatable door structure in each vestibule, means for rotating each of said door struc- `tures a part revolution intermittently to periodically charge and discharge said furnace, and means for locking said door structures against rotation'during idle periods of their intermittent rotation.

4. In a heat-treating furnace or the like, means for charging vand discharging material therefrom without substantial heat losses or the introduction of deleterious gases comprising vestibule structure at each adit and exit of the furnace, a rotatable shaft and door naps supported thereby constituting rotatable door structure in each vestibule, means for rotating each of said shafts a part revolution intermittently to periodically charge and discharge material from said furnace, each of said flaps on the door structures in each adit vestibule having openings therein, members serving normally to close said openings, and means to move said members in turn to expose the respective openings covered thereby to facilitate scavenging deleterious gases from charges in each adit located vestibule just prior to. the entry of the charges into said furnace.

5. In a heat-treating furnace or the like having a continuously driven conveyor therein, means for charging said furnace with material to be treated and discharging treated material therefrom without substantial heat losses or the introduction of deleterious gases into said furheat and gas sealing means in conjunction with said doors and vestibules.

6. In a heat-treating furnace or the like having a continuously driven conveyor therein, means for charging said furnace with material to be treated and discharging treated material therefrom without substantial heat losses or the introduction of deleterious gases into s'aid furnace, said means comprising a vestibule at each material-charge adit and at each material-discharge exit of said furnace, conveyor means for delivering charge material to each adit-located vestibule, conveyor means for receiving discharged charges from each exit-located vestibule, conveyor means within e? ch vestibule, revolving doors within each vestibule, means for intermittently rotating said doors a part revolution at a time, means for locking each of said doors against accidental rotation during their idling periods of intermittent rotation, heat and gas sealing means in conjunction with said doors ,and vestibules, and cam-controlled means assovsaid furnace, each said structure comprising a vestibule, a plurality of door flaps hingedly supported from a rotatable axle carried in said vestibule, and means for bracing said flaps at fixed angles with respect to each other, said lastnamed means being removable at least in part to facilitate the folding of at least one of said flaps against one of the remaining bracedv flaps.

WILLIAM J. KRAILING. 

